Epics are large user stories, typically ones which are too big to implement in a single iteration and therefore they need to be disaggregated into smaller user stories at some point. Epics are typically lower priority user stories because once the epic works its way towards the top of the work item stack, see Figure 4 , it is reorganized into smaller ones. It doesn't make sense to disaggregate a low-priority epic because you'd be investing time on something which you may never get to addressing, unless a portion of the epic is high priority and needs to be teased out. Remember to defer commitment, in this case model on a just-in-time (JIT) basis, to increase your overall productivity. 8. Themes A theme is a collection of related user stories. For example, for a university registration system there might be themes around students, course management, transcript generation, grade administration, financial processing. Themes are often used to organize stories into releases or to organize them so that various subteams can work on them.